Such friction linings are familiar, for instance, from U.S. Pat. No. 6,534,565 Bl, as the so-called paper-based linings, particularly for application as friction linings in wet clutches like converter lockup clutches, etc. Among others, the manufacturing process entails pressing a thin friction lining made of a mixture of cellulose fibers, aramid (a thermosetting resin) fibers, fillers and resin in a hot-pressing process; the lining is subsequently stuck on a wet clutch disc. By pressing the disc with friction surface against a mating surface, the torque to be transmitted will be transmitted partly by setting default slip, in particular during the closing and opening states of the wet clutch.
With an increase in torque to be transmitted by the wet clutch, the demands posed on the properties of friction surfaces increase in the process, in particular on their durability under high-pressure. Thus, the properties of ingredients like fillers, which normally decisively influence the coefficient of friction, are not adequate.